The present invention generally relates to helical scan type magnetic recording and/or reproducing apparatuses, and more particularly to a magnetic recording and/or reproducing apparatus which can be downsized to a large extent.
Presently, there are several standardized systems for video tape recorders. The pattern of video tracks, an audio track, and a control track on a magnetic tape, the location of a control head, and the like are standardized in each of the standardized systems. On the other hand, there has been a recent development in downsizing the video tape recorder, by maintaining magnetic tape compatibility with the existing video tape recorder, that is, without changing the pattern of video tracks and the like on the magnetic tape.
As one method of downsizing the video tape recorder with the above described conditions still satisfied, there is a method of increasing the number of video heads, reducing the diameter of a tape guide drum, and increasing the angular range over which the magnetic tape is wrapped around the guide drum. For example, there was a method of providing four video heads at a 90.degree. interval, reducing the diameter of the guide drum to 2/3 the diameter of the existing guide drum, and wrapping the magnetic tape around the guide drum over an angular range of approximately 270.degree. instead of the angular range of approximately 180.degree. which is employed in the existing video tape recorder. In this case, the four video heads were switched so as to operate with an interval of 270.degree.. According to this method, the video tracks are formed on the magnetic tape with a pattern which is the same as the pattern which is in conformance with the existing standard, and the magnetic tape compatibility is maintained. Moreover, the video tape recorder can be downsized, because of the downsized guide drum.
As a method of wrapping the magnetic tape around the guide drum over the angular range of approximately 270.degree., one may consider employing the existing tape loading system for wrapping the magnetic tape around the guide drum over the angular range of approximately 180.degree.. In this case, loading poles must travel over a greater distance in order to wrap the magnetic tape over the angular range of approximately 270.degree.. In addition, the guide drum must be inclined by approximately 40.degree. which is a large angle compared to the inclination of the existing guide drum. Furthermore, tape guide poles which are respectively located at positions where the magnetic tape begins to make contact with the guide drum and terminates the contact, must be inclined by an angle of 27.degree. which is a large angle compared to the inclination of the guide poles in the existing tape loading system. Thus, it would be impractical to employ the existing tape loading system for the purpose of wrapping the magnetic tape around the guide drum over the angular range of approximately 270.degree..
The present inventor has devised various arrangements for the tape guide poles which wrap the magnetic tape around the guide drum over the angular range of approximately 270.degree., where the inclination of the guide drum is maintained the same as the inclination of the existing guide drum, by taking into consideration the possibility of realizing automatic tape loading operation with these arrangements. However, the number of guide poles which are arranged at the positions where the magnetic tape begins to make contact with the guide drum and terminates the contact, is generally large. Moreover, the guide poles are arranged quite separated from the guide drum. Therefore, although the guide drum itself could be downsized, the tape loading mechanism became complex because a large number of guide poles were arranged separated from the guide drum around the periphery of the guide drum. As a result, it was difficult to realize automatic loading of the magnetic tape. Further, there was a disadvantage in that the whole apparatus could not be downsized in accordance with the downsized guide drum